Apparatus for the recovery of gold



Jan. 10, 1933. A. J. CLARK ET AL APPARATUS FOR THE RECOVERY OF GOLD Filed Jan. 2, 1932 Sheets-Sheet t]: ghrizventors Warren/ 11. Todd Gttorucgs.

Jan. 10, 1933. A, J CLARK ET AL 1,894,159

APPARATUS FOR THE RECOVERY OF GOLD Filed Jan. 2, 1932 4 Sheets-Sheet 2 BnnentorS H q I attorneys.

Jan. 10, 1933. ARK ETAL 1,894,159

APPARATUS FOR THE RECOVERY OF GOLD Filed Jan. 2, 1932 4 Sheets-Sheet 4 a I 61 dimers warm/E Todd Patented Jan. 10, 1933 UNETED STATES PATENT OFFEE ALLAN J. CLARK AND "WARREN TODD, OF LEAD, SOUTH DAKOTA APPARATUS FOR THE RECOVERY OF GOLD Application filed January 2, 1932.

The present invention relates to improve ments in apparatus for the recovery of gold. In recovering free or uncombined gold H p from its ores, two methods have been followed from earliest times. Both of these methods begin with a preliminary crushing of the ore to liberate the gold particles from the barren gangue. F The first method employed gravity as a means for collecting the gold, which was settled out in riftles or cleats attached to the bottom of a small launder, or otherwise by spreading the pulp over a roughened surface, such as carpet, corduroy or, in ancient times, sheep skins which were essentially fine riilies and in which the gold settled out.

The second method consisted in bringing the particles of gold in contact with mercury; the resulting amalgam being collected by suitable means. This is the amalgamation method, which is usually carried out by first adding mercury to the ore during its grinding or immediately thereafter; and second, 7 collecting the amalgam so formed by flowing the pulp, in a thin sheet, over a considerable area of suitable surface, for instance, copper plates or, preferably, silver-plated copper plates, which surface is itself covered with a thin layer of amalgam kept at a suitable consistency by the occasional addition of mercury.

Sometimes, and this more particularly with rotary grinding machines, such as rod mills, ball mills, tube mills, the addition of mercury to the mill results in the forming of much amalgam within the machine and, upon discharge, some of this settles out in the discharge box before the pulp can be spread over amalgam plates. In this box, there also accumulates fragments of the grinding media (iron or fiints) and a concentrate of the heavier pyritic minerals of the ore, the whole making a mixture requiring considerable screening, washing, etc. before the valuable amalgam could be recovered. This manipulation increased the hazard of loss through theft and made supervision difficult.

We are aware that many amalgamators have been proposed including the Pierce and the Atwood, but all such amalgamators have Serial No. 584,580.

substantially-failed in practice because the amalgamator was too small for the volume of pulp passing through it; and the velocity of flow was so great as to actually wash away some of the mercury.

It is an object of the present invention to correct previous difficulties in the amalgamation method of recovering gold whereby increased recovery of the metal is had and in- A creased security from tampering obtained.

The invention also contemplates simplifying preparation of the crude amalgam for the market.

With the foregoing and other objects in view, the invention will be more fully described hereinafter, and will be more particu larly pointed out in the claims appended hereto.

In the drawings, wherein like symbols refer to like or corresponding parts throughout the several views,

Figure 1 is a perspective view of an improved amalgamator constructed in accordance with the present invention.

Figure 2 is also a perspective view with certain parts removed showing the interior construction.

Figure 3 is a vertical section taken on the line 33 in Figure 1.

Figure 4 is a similar section taken on the line 4-4; in Figure 3.

Figure 5 is also avertical section taken on the line 5-5 in Figure at.

Figure 6 is a perspective view of the discharge box tray.

Figure 7 is a perspective view of the first launder tray.

Figure 8 is a similar view, with. portions cut away, showing the amalgam plate for the second launder.

Figure 9 is a perspective view of the chip screen, and

Figure 10 is a bottom perspective view of the guard screen.

Referring more particularly to the drawings,11 represents the discharge from a rod mill or the like whereby the thick pulp, which is a mixture of ground ore particles with water. to which mercury has been added. is caused to discharge into the amalgamator.

Such thick pulp is directed by the discharge 11 onto the chip screen, shown more particularly in Figure 9, and composed of a perforated bottom 12, low rear and side walls 13 and 14, respectively, which are also perforated, the perforated high front wall and. the opposite side wall 16 of substantially equal hei ht with the front wall and also being per orated.

As shown in Figure 3, this chip screen rests upon two or more rods 17 and lies in a pulp box or first launder made up of the front Wall 18, the rear wall 19, a fixed side wall 20 and a removable side wall 21. The side wall 21 is shown as being slidable vertically ingrooves 22 in the box so as to enableit to be removed to ermit withdrawal of the tray which is contained in this box, as hereinafter described. Throughthe end wall 21 is connected a hose or the like 23 connected to a source of water supply, and this hose is connected beneath the level of the guard screen, which is shown more particularly in Figure 10, as consisting of a perforated plate 24 having down-turned flanges 25 and 26 on two sides, which flanges are adapted to receive a fastening means whereby the guard screen is permanently secured to parts of the pulp box; not, however, to the removable end wall 21. In the guard screen is a large opening for receiving the chip screen 12, the association of these two screens being shown in Fi ures 1 and 3. In the rear wall 19 of the pu p box may be made a curved cut-away portion 27 to receive the discharge pipe 11 rom the mill.

As shown more particularly in Figure 3, the rods 17 are supported in the side walls 28 of the tray, the walls having semi-circular grooves 29 to fit about the rods 17.

The tray, which is shown more particularly in Figure 6, includes the side walls 28, the bottom 30 and the end walls 31 and 32. The end wall 31 is provided with a cut-away portion 33 to receive the pipe or hose 23.

The other end wall 32 forms a weir having a lip 34 which may be cut and pressed outwardly from the metal of which the tray is made, and which lip forms an overflow for the pulp from the tray into the first launder which is a trough or flume for conve ing the water and the pulp.

his first launder may be built as a part of the pulp box or built separately and united therewith and which consists of a bottom 35, side walls 36 and 37 and end walls 38 and 39. The side wall 37 is a continuation of the side wall 20 of the pulp box, and in this side wall 20 is made an opening 40, shown in Fig ure 2, for receiving therethrongh the lip 34 of the copper tray 30.

In the launder 36 is also a copper tray, shown more particularly in Figure 7, and comprising a bottom 41, end walls 42 and 43, which are preferably provided with perforations 44, an outer continuous side wall 45 extending from one end wall 42 to the other end wall 43, and an inner interrupted side wall 46 extending up from the bottom 41 at an intermediate portion only of the tray, but terminating short of both end walls, whereby to provide spaces at opposite sides of the inner wall 46 for the fiow of the material and for receiving the lip 34, as shown in Figure 2.

Above the tray 41 in the first launder is a locking cover 47 provided with loops or eyes 48 to slidingly receive therethrough a locking rod 49 seated in sockets 50 in the end walls 38 and 39. The rod 49 carries a slotted hasp 51 which is pivoted thereto, as indicated in Figures 1 and 4, such hasp being adapted to engage over an eye 52 through which a padlock 53 maybe passed. In this. way, access to the launder, except by authorized persons,

is prevented.

The second launder extends substantially at right angles to the first launder and connects through an opening 54 in the side wall 37. This second launder is included within a bottom 55 and side walls 56 and 57 In the launder is an amalgam plate 58, shown more particularly in, Figure 8. The plate is an elongated wide thin plate substantially the dimensions of the bottom 55 of the launder.

Over the top of this launder are secured wire or other guards 59 which may be hinged, as indicated at 60, to one of the walls 57 whereby the same may be swung upwardly to give access to the interior of the launder for the purpose of removing the amalgam plate 58.

the mill through the discharge 11 will fall upon the chip screen which removes the scrap iron or flint fragments of the grinding media. The pulp passes through the screen to the compartment below such screen, which compartment contains an amalgamated cop er box or tray 30. Through the hose 23, a ditional water is added, and the pulp flows over the lip 34 of the tray 30 into the launder 36, which'also contains the amalgamated copper tray 41.

The direction of flow changes as the pulp flows through the launder 36 and changes again as it passes from the launder 36 to the second launder 55, which is furnished with the amalgamated silver-plated copper plate 58.

The chip screen 12 must be emptied several times daily. It is therefore made separate from the guard screen 24, which guard screen is preferably of larger mesh and sur-v rounds the chip screen 12. The guard screen and the various covers are all designed to give security from tampering, and they may be locked in place as indicated.

.In practice, the coarser'gold will be caught in the launders consisting of the trays and ll, and such gold is allowed to accumulate in these trays for several days at a time. However, the plate 58 in the launder is removed for cleaning several times daily.

In recovering amalgam, the mill is shut down and the water supply is shut oif. The chip screen 12 is removed. The end board 21 of the first launder nearest the hose 23 is removed and the amalgam box or tray 30 is withdrawn through the opening thus formed and removed, without further handling, to the cleanup room.

The guard cover s7 is then unlocked and removed, as indicated in Figure 2, and the tray 41 is lifted out and taken to the cleanup room.

The improved device provides means of increasing the catch of amalgam, first, by causing the pulp to change direction several times, each change resulting in a retarded velocity of flow and afiording opportunity for amalgam to build up on the plate; second, by lining the launders with amalgamated trays, facilitating the a tachment of amalgam particles, such trays being of sufficient depth to retain a considerable body of amalwithout loss; and third, by removing crap iron, etc. at the point of discharge of the mill, thus keeping the recovered material clean.

By providing a practical. and adequate system of screens and covers, susceptible of looking, security from theft is increased.

It will be understood that the improved method and apparatus is applicable to other crushing or grinding machines besides rod mills, ball mills, tube mills and rotary grinders.

It will be noted that in the improved device, trays are used instead of plates. The plates, commonly used, accumulate a layer of amalgam of but slight thickness and must be frequently cleaned to keep this from scouring off the inclined surfaces. In providing sides to the trays, we make it possible for amalgam to build up upon itself to a considerable depth securing a three-dimensional instead of a two-dimensional body of amalgam. At the same time, we protect the larger amount of amalgam from tampering.

It will be obvious that various changes in the construction, combination and arrangement of parts could be made, which could be used without departing from the spirit of our invention, and we do not mean to limit the invention to such details, except as particularly pointed out in the claims.

Having thus described our invention, what we claim and desire to secure by Letters Patent of the United States is 1. In apparatus for the recovery of gold, a pulp box, a mill discharge to the pulp box, a perforated guard screen permanently mounted in said box, a removable end wall for said box, an amalgamated tray movable through the end wall and situated below said guard screen, a chip screen removably mounted above the tray and beneath the discharge, a supply of water to said tray, and launders connecting with said tray.

2. In apparatus for the recovery of gold, a pulp box, a guard screen secured permanently therein and having a cut-away portion, rods removably mounted through said box, a chip screen removably mounted on said rods, a mill discharge above said chip screen, a tray below said guard screen locked in place by said rods, and launders connecting with said tray.

3. In apparatus for the recovery of gold, a pulp box, a removable end wall for said box, a perforated guard screen secured permanently to said box, and having a cut-away portion, rods removably mounted in said box below said guard screen, a chip screen removably carried on said rods, a mill discharge above said chip screen, an amalgamated tray mounted in the lower portion of said box and removable through the end wall thereof, said tray having indented portions interlocking with said rods, and launders connected with said tray.

4. In apparatus for the recovery of gold, a pulp box, a mill discharge thereto, an amalgamated tray in said box having a lip in its discharge end, means for screening the pulp passing to said tray, a launder extending at substantially right angles to said pulp box, an amalgamated tray in said launder underlying the lip of the first tray, and having inlet and discharge openings, and a third launder connecting with the discharge of the second tray and being disposed angularly to the second launder.

ALLAN J. CLARK. WARREN H. TODD. 

